#2113 Membranoproliferative glomerulonephritis experience over 20 years in a tertiary centre in the United Kingdom

Abstract

Abstract Background and Aims Membranoproliferative Glomerulonephritis (MPGN) is a histological pattern of injury which typically accounts for light microscopy findings on 1-3% of kidney biopsies. It is classified based on immunofluorescence into complement-mediated, immune complex-mediated (IC) and immunofluorescence negative. The underlying aetiologies such as C3 Glomerulopathy are rare diseases, and thus longitudinal real-world experience in terms of underlying causes, treatment and outcomes is valuable. Method This study presents a retrospective review of biopsy data from January 2000 through to December 2020 in a tertiary renal referral centre in the United Kingdom (UK). This review was conducted using the organisation's biopsy database, with patient demographics and clinical information obtained from the Electronic Patient Record. All patients with an MPGN pattern on biopsy were reviewed. Those with new MPGN post-transplant, with an MPGN pattern on biopsy but subsequently diagnosed as IgA Nephropathy, and with an MPGN pattern but a known lupus diagnosis, were excluded. Results A histological finding of MPGN on kidney biopsy was found in 67 patients. Of these, 41 remained in the study following application of the exclusion criteria, with an additional 3 excluded as there was insufficient information available for classification in their biopsy reports. Of the 38 remaining, 28 had IC MPGN and 10 had C3 Glomerulopathy (C3G) - 8 with C3 Glomerulonephritis (C3GN) and 2 with C3 Dense Deposit Disease (DDD). Median follow up was 72 (range 45-126) months. Median age was 64 years in the IC MPGN and 55 years in the C3G groups (p 0.125). The majority in both groups were female, 60.7% (17) and 60% (6) respectively. There was no significant difference in renal function, blood pressure, or proteinuria at presentation between the groups. MPGN was associated with infections in 8 patients (21.1%), connective tissue disease in 3 patients (7.9%), monoclonal gammopathies or haematological malignancies in 8 patients (21.1%), and 2 had identified complement deficiencies (5.3%). Over the study period 47.4% (18) of patients progressed to end stage kidney disease and 50% (19) died. There was no significant difference in these outcomes between the IC MPGN and the C3G groups. Progression to renal replacement therapy (RRT) was seen in 42.9% (12) of the IC MPGN group, and 60% (6) of the C3G group (p=0.287). This included two patients who received a kidney transplant (both in the C3G group), one of whom developed recurrence during the available follow up. Conclusion This study adds a UK perspective with long term data and outcomes in a rare condition. Almost half of patients progressed to RRT and half of patients died during the follow-up period. These outcomes were seen at similar rates in those with IC MPGN and those with C3G. A variety of associated conditions were observed, and the low number of complement deficiencies identified is likely due to the historical nature of the review with reduced screening for complement abnormalities and genetics in the earlier period. Outcomes on follow-up: